KR20230122969A - Multilayer ceramic capacitor and method for manufacturing multilayer ceramic capacitor - Google Patents

Abstract

A multilayer ceramic capacitor in which penetration of moisture into a capacitive element is suppressed. The external electrode includes Ni particles and Sn particles, and the capacitance element and the external electrode are cut at a point that is 1/2 the length of the width direction of the capacitance element, when viewed from a cut plane parallel to the side surface of the capacitive element The electrode is formed in a C shape on an end surface of the capacitive element and a main surface connected to both sides of the end surface, and the C-shaped external electrode includes a first area and a second area completely surrounding the first area, Area 2 is a region in which Sn particles are unevenly distributed, and when a square measurement area of 10 μm × 10 μm is arbitrarily selected from the second area exposed on the cut surface, the sum of the area of Ni particles and the area of Sn particles exposed in the measurement area When the area of Sn particles for is 90% or more, and the first area is randomly selected from the first area exposed on the cut surface, a square measurement area of 10 μm × 10 μm is selected, the area of Ni particles exposed in the measurement area and Sn It is assumed that the area of the Sn particles is less than 90% of the total area of the particles.

Description

Multilayer ceramic capacitor and manufacturing method of multilayer ceramic capacitor

The present invention relates to a multilayer ceramic capacitor in which at least two external electrodes are formed on the outer surface of a capacitive element. Further, the present invention relates to a method for manufacturing a multilayer ceramic capacitor suitable for manufacturing the multilayer ceramic capacitor of the present invention.

Multilayer ceramic capacitors are widely used in electronic devices and electrical devices. A multilayer ceramic capacitor including a general structure is disclosed in Patent Document 1 (Japanese Unexamined Patent Publication No. 2016-58719). 5 shows a multilayer ceramic capacitor 1000 disclosed in Patent Literature 1.

The multilayer ceramic capacitor 1000 includes a ceramic body 103 (capacitance element) in which a dielectric layer 101 (ceramic layer) and internal electrodes 102 are stacked. External electrodes 104 are formed at both ends of the ceramic body 103 .

The external electrode 104 includes, for example, an external electrode body 105 formed by baking a conductive paste containing Ni particles, etc., a plating layer 106, for example, a first layer of Ni, and a second layer, for example, It is formed in a multi-layered structure consisting of a plating layer 107 of Sn or the like as a layer.

Japanese Unexamined Patent Publication No. 2016-58719

In the conventional multilayer ceramic capacitor 1000 described above, when the plating layer 106 as the first layer or the plating layer 107 as the second layer is formed, moisture contained in the plating bath passes through the external electrode body 105 to form the ceramic body 103 ) and IR (insulation resistance) may be deteriorated.

Accordingly, an object of the present invention is to provide a multilayer ceramic capacitor in which moisture does not penetrate easily into a capacitor when a plating layer is formed on an external electrode or when a finished product is used.

On the other hand, in the multilayer ceramic capacitor 1000 of Patent Literature 1, penetration of moisture into the ceramic body 103 (capacitance element) is suppressed by a means different from that of the present invention.

In order to solve the above-mentioned conventional problems, a multilayer ceramic capacitor according to an embodiment of the present invention has a plurality of laminated ceramic layers and a plurality of internal electrodes, and a pair of main surfaces facing each other in the height direction. ), a pair of end faces facing each other in the longitudinal direction orthogonal to the height direction, and a pair of side surfaces facing each other in the width direction orthogonal to the height and length directions; A multilayer ceramic capacitor including at least two external electrodes formed on a surface, wherein the external electrodes include Ni particles and Sn particles, and the capacitance element and the external electrode are cut at a position that is 1/2 the length of the width direction of the capacitance element. When viewing a cut plane parallel to the side surface of one capacitive element, the external electrode is formed in a C shape on the end surface of the capacitance element and the main surface connected to both sides of the end face, and the C-shaped external electrode is formed in a first region; It includes a second region completely surrounding the first region, the second region is a region in which Sn particles are localized, and when a square measurement region of 10 μm × 10 μm is arbitrarily selected from the second region exposed on the cut surface, the measurement The area of Sn particles relative to the sum of the area of Ni particles and the area of Sn particles exposed in the area is 90% or more, and the first area randomly selects a square measurement area of 10 μm × 10 μm from the first area exposed on the cut surface. In this case, it is assumed that the area of the Sn particles is less than 90% of the total area of the Ni particles and the area of the Sn particles exposed in the measurement area.

In addition, a method of manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention has a plurality of laminated ceramic green sheets and a plurality of conductive paste layers for internal electrodes, a pair of main surfaces facing each other in the height direction, and a height direction manufacturing an unsintered capacitance element having a pair of end faces facing each other in the longitudinal direction orthogonal to and a pair of side surfaces facing each other in the height direction and the width direction orthogonal to the length direction; A step of manufacturing a conductive paste for external electrodes containing particles and Sn particles, a step of applying the conductive paste for external electrodes to at least the end face of the unsintered capacitance element, and the main surface and side surface connected to the end face in a cap shape; A method for manufacturing a multilayer ceramic capacitor including a step of simultaneously firing an unsintered capacitance element and conductive paste for external electrodes, wherein the conductive paste for external electrodes contains Sn particles relative to the sum of the weight of Ni particles and the weight of Sn particles contained therein. The weight of is 1 to 15% by weight.

In the multilayer ceramic capacitor according to one embodiment of the present invention, penetration of moisture into the capacitor is suppressed when a plating layer is formed on the outer surface of the external electrode or when the finished product is used.

In addition, the multilayer ceramic capacitor according to one embodiment of the present invention can be used as it is without forming a plating layer on the outer surface of the external electrode because Sn, which is excellent in solder wettability, is unevenly distributed in the second region exposed on the outer surface of the external electrode. . That is, without forming a plating layer on the outer surface of the external electrodes, the external electrodes can be joined to the mounting electrodes on the substrate by, for example, reflow soldering.

According to the manufacturing method of the multilayer ceramic capacitor according to one embodiment of the present invention, the multilayer ceramic capacitor of the present invention can be manufactured with high productivity.

1 is a perspective view of a multilayer ceramic capacitor 100 .
2 is a cross-sectional view of the multilayer ceramic capacitor 100 .
3(A) to (C) are cross-sectional views showing steps in an example of a method for manufacturing the multilayer ceramic capacitor 100, respectively.
4 is a cross-sectional view of the multilayer ceramic capacitor 200.
5 is a cross-sectional view of a conventional multilayer ceramic capacitor.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated together with drawing.

On the other hand, each embodiment shows an embodiment of the present invention by way of example, and the present invention is not limited to the content of the embodiment. In addition, it is also possible to implement by combining the content described in other embodiments, and the content of implementation in that case is also included in the present invention. In addition, the drawings are intended to aid understanding of the specification, and may be drawn, and the ratio of dimensions between drawn components or components may not match the ratio of their dimensions described in the specification. In addition, there are cases where components described in the specification are omitted from the drawing or drawn with the number omitted.

[First Embodiment]

1 and 2 show a multilayer ceramic capacitor 100 according to the first embodiment. However, FIG. 1 is a perspective view of the multilayer ceramic capacitor 100 . 2 is a cross-sectional view of the multilayer ceramic capacitor 100 .

In the drawing, the height direction (T), length direction (L), and width direction (W) of the multilayer ceramic capacitor 100 are shown, and these directions are sometimes referred to in the following description. Meanwhile, in the present embodiment, the stacking direction of the ceramic layer 1a, which will be described later, is defined as the height direction T of the multilayer ceramic capacitor 100.

The multilayer ceramic capacitor 100 includes a capacitance element 1 having a rectangular parallelepiped shape. The capacitance element 1 includes a pair of main surfaces 1A and 1B facing each other in the height direction T, and a pair of end faces 1C facing each other in the longitudinal direction L orthogonal to the height direction T, 1D) and a pair of side surfaces 1E and 1F facing each other in the width direction W orthogonal to both the height direction T and the length direction L.

As indicated by the dashed-dotted arrows X-X in FIG. 1, the cross-sectional view of FIG. 2 described above is cut at half the length of the width direction (W) of the capacitor 1, and the side surface of the capacitor 1 ( 1E, 1F) is a cross-sectional view of the multilayer ceramic capacitor 100 in parallel. On the other hand, this cut surface may be called a first cut surface.

The dimensions of the multilayer ceramic capacitor 100 are arbitrary. However, the dimension in the height direction T can be, for example, about 0.1 mm to 2.5 mm. The dimension in the longitudinal direction L can be, for example, about 0.1 mm to 3.2 mm. The dimension in the width direction W can be, for example, about 0.1 mm to 2.5 mm.

The capacitance element 1 is formed by stacking a plurality of ceramic layers 1a and a plurality of internal electrodes 2 and 3.

Although the material of the capacitance element 1 (ceramic layer 1a) is arbitrary, for example, dielectric ceramics containing BaTiO ₃ as a main component can be used. However, instead of BaTiO _{3 ,} dielectric ceramics containing other materials as main components, such as CaTiO ₃ , SrTiO ₃ , and CaZrO ₃ , may be used.

The thickness of the ceramic layer 1a is arbitrary, but may be, for example, about 0.3 μm to 2.0 μm in the effective region of capacitance formation where the internal electrodes 2 and 3 are formed.

Although the number of layers of the ceramic layer 1a is arbitrary, for example, it can be 1 to 6000 layers in the effective region of capacitance formation where the internal electrodes 2 and 3 are formed.

On both upper and lower sides of the capacitive element 1, internal electrodes 2 and 3 are not formed, and an outer layer (protective layer) composed only of the ceramic layer 1a is provided. The thickness of the outer layer is arbitrary, and may be, for example, 15 μm to 150 μm. On the other hand, the thickness of the ceramic layer 1a in the outer layer region may be larger than the thickness of the ceramic layer 1a in the effective capacitance forming region where the internal electrodes 2 and 3 are formed (however, in FIG. 2, the outer layer region and The thickness of the ceramic layer (1a) in the effective area is shown as the same thickness). Also, the material of the ceramic layer 1a in the outer layer region may be different from that of the ceramic layer 1a in the effective region.

Although the material of the main component of the internal electrodes 2 and 3 is arbitrary, Ni was used in this embodiment. However, you may use other metals, such as Cu, Ag, Pd, and Au, instead of Ni. In addition, Ni, Cu, Ag, Pd, Au, etc. may be an alloy with another metal.

The thickness of the internal electrodes 2 and 3 is arbitrary, and may be, for example, about 0.3 μm to 1.5 μm.

The size of the gap between the internal electrodes 2 and 3 and the side surfaces 1E and 1F of the capacitive element 1 is arbitrary, and may be, for example, about 10 μm to 200 μm. In addition, the size of the gap between the internal electrode 3 and the end surfaces 1C and 1D of the capacitive element 1 is arbitrary, and may be, for example, about 0.5 μm to 300 μm.

External electrodes 4 and 5 are formed on the outer surface of the capacitive element 1 .

The external electrode 4 is formed on the end face 1C of the capacitive element 1 . The external electrode 4 is formed in a cap shape, and the edge portion extends from the end face 1C of the capacitance element 1 to the main surfaces 1A and 1B and the side surfaces 1E and 1F. .

The external electrode 5 is formed on the end face 1D of the capacitive element 1 . The external electrode 5 is formed in a cap shape, and the edge portion extends from the end face 1D of the capacitive element 1 to the main surfaces 1A and 1B and the side surfaces 1E and 1F.

In the multilayer ceramic capacitor 100, an internal electrode 2 extending to an end face 1C of a capacitor 1 is connected to an external electrode 4. The internal electrode 2 drawn out to the end face 1D of the capacitance element 1 is connected to the external electrode 5.

The external electrode 4 and the external electrode 5 have the same structure.

When the first cross section of the multilayer ceramic capacitor 100 shown in FIG. 2 is viewed, the external electrodes 4 and 5 each have a letter C shape. In addition, it can be said that the external electrodes 4 and 5 each have a letter U shape. In addition, it can be said that the external electrodes 4 and 5 each have a U-shape.

In the first cross section of FIG. 2 , the external electrodes 4 and 5 each include a first region 6 and a second region 7 . In this embodiment, the second area 7 completely surrounds the first area 6 .

The second region 7 includes an inner region 7a in contact with the capacitive element 1 and an outer region 7b not in contact with the capacitive element 1 .

Both the first region 6 and the second region 7 contain Ni and Sn. However, the second region 7 is a region in which Sn is unevenly distributed, and when a square measurement region of 10 μm × 10 μm is arbitrarily selected from the second region 7 exposed on the first cut surface, Ni exposed in the measurement region The area of Sn to the sum of the area of and the area of Sn is 90% or more. On the other hand, the first region is the area of Sn relative to the sum of the area of Ni and the area of Sn exposed in the measurement region when a square measurement region of 10 μm × 10 μm is arbitrarily selected from the first region exposed on the first cross section. is less than 90%. On the other hand, the area of Ni and the area of Sn are calculated and measured from the detection ratio of each atom in composition analysis with a scanning electron microscope.

A case where the boundary between the first region 6 and the second region 7 is ambiguous can be considered, but even in such a case, the multilayer ceramic capacitor 100 has the second region 7 covering the first region 6. completely surround

In addition, from another point of view, the area occupied by Sn per unit area of the external electrodes 4 and 5 exposed on the first cut surface is larger on the outer side (the side in contact with the capacitive element 1 and/or the side in contact with the atmosphere). , the inner side is smaller.

The thickness of the external electrodes 4 and 5 is arbitrary, and may be, for example, about 5 μm to 150 μm. Further, the thickness of the first region 6 and the thickness of the second region 7 (the thickness of the inner region 7a and/or the thickness of the outer region 7b) are also arbitrary. However, the conductive paste for external electrodes 4 and 5 contains Ni particles and Sn particles, but the weight of Sn particles relative to the sum of the weight of Ni particles and the weight of Sn particles contained in the starting material The higher the ratio, the greater the thickness of the second region 7 (the thickness of the inner region 7a and/or the thickness of the outer region 7b).

In the multilayer ceramic capacitor 100 according to the present embodiment having the above structure, Sn having excellent solder wettability is unevenly distributed in the second region 7 (outer region 7b) exposed on the outer surface of the external electrodes 4 and 5. Therefore, the outer surfaces of the external electrodes 4 and 5 can be used without forming a plating layer. That is, since solder wettability is sufficiently contained even without forming a plating layer on the outer surface of the external electrodes 4 and 5, the external electrodes 4 and 5 are attached to mounting electrodes on a substrate or the like (not shown), for example It can be joined by reflow solder.

In this case, the overall dimensions of the multilayer ceramic capacitor 100 can be reduced and/or the capacitance can be increased as the plating layer is not formed on the external electrodes 4 and 5 . That is, generally, the dimensions of an electronic component are defined by including the dimensions of the external electrodes including the plating layer, but (a) if the capacitance is constant, the overall dimensions can be reduced as the plating layers are not formed on the external electrodes 4 and 5. (b) If the overall dimensions are constant, the capacitance can be increased by increasing the dimensions of the capacitance element 1 as the plating layer is not formed on the external electrodes 4 and 5.

In addition, the multilayer ceramic capacitor 100 can be used after forming one layer or a plurality of plating layers on the external electrodes 4 and 5 . For example, a Sn plating layer may be formed on the outer surface of the outer region 7b of the second region 7 of the external electrodes 4 and 5 and used. Alternatively, a Sn plating layer may be formed as a first layer and a Sn plating layer may be formed as a second layer on the outer surface of the outer region 7b of the second region 7 of the external electrodes 4 and 5. On the other hand, the number or material of the plating layer is not limited thereto and can be variously changed.

In the multilayer ceramic capacitor 100, when plating layers are formed on the external electrodes 4 and 5, penetration of moisture into the capacitor element 1 is suppressed. Although this effect will be explained in detail later (moisture resistance load test), the inner region 7a in which Sn is unevenly distributed in the second region 7 of the external electrodes 4 and 5 is absorbed by the capacitor 1. It is thought that it greatly contributes to suppressing this intrusion. On the other hand, regarding the degree of uneven distribution of Sn in the second region 7, it is considered necessary and sufficient condition that the area of Sn is 90% or more of the total area of Ni and Sn.

(An Example of Manufacturing Method of Multilayer Ceramic Capacitor 100)

An example of a manufacturing method of the multilayer ceramic capacitor 100 according to the first embodiment will be described with reference to FIGS. 3(A) to (C).

Meanwhile, in an actual multilayer ceramic capacitor manufacturing line, it is common to collectively manufacture a plurality of multilayer ceramic capacitors using a mother ceramic green sheet, but here, for convenience of explanation, a case of manufacturing one multilayer ceramic capacitor is described. Explain with an example.

First, the unsintered capacitance element 11 shown in FIG. 5(A) is fabricated.

Although not shown, a ceramic slurry is produced by preparing dielectric ceramic powder, binder resin, solvent, and the like, and wet-mixing them.

Next, a ceramic green sheet 12 is manufactured by applying a ceramic slurry on a carrier film in a sheet shape using a die coater, a gravure coater, a micro gravure coater, or the like, and drying the ceramic slurry.

Next, in order to form the internal electrodes 2 and 3 on the main surface of the predetermined ceramic green sheet 12, the conductive paste for the internal electrodes prepared in advance is applied (eg, printed) in a desired pattern shape to obtain conductivity for the internal electrodes. A paste layer 13 is formed. However, the conductive paste for internal electrodes is not applied to the ceramic green sheet 12 serving as the outer layer. On the other hand, as the conductive paste for internal electrodes, for example, a mixture of metal particles (Ni particles, etc.), a binder resin, a solvent, and the like can be used.

Next, the ceramic green sheets 12 are laminated in a predetermined order and heat-compressed to integrate them, thereby fabricating the unfired capacitor 11 shown in FIG. 5(A).

Next, a conductive paste for external electrodes is prepared. The conductive paste for external electrodes includes Ni particles and Sn particles. The conductive paste for external electrodes further contains, for example, a binder resin and a solvent. The conductive paste for external electrodes may contain a glass component. By mixing these materials, a conductive paste for external electrodes is prepared. The blending ratio of Ni particles, Sn particles, binder resin, solvent, etc. can be appropriately selected.

However, the conductive paste for external electrodes in this embodiment contains more Sn particles than Ni particles in weight. Specifically, the conductive paste for external electrodes contains 1 to 15% by weight of Sn particles when the total weight of Ni particles and Sn particles is 100% by weight. This is to ensure that the second area 7 completely surrounds the first area 6 in the first cut plane shown in FIG. 2 . That is, if the amount of Sn particles in the conductive paste for external electrodes is insufficient, formation of the second regions 7 in which Sn is unevenly distributed becomes insufficient. For example, if Sn particles are insufficient, even if the outer region 7b is formed as the second region 7, the inner region 7a may be incompletely formed or the inner region 7a may not be formed. . Incomplete formation of the inner region 7a refers to a case in which the inner region 7a is intermittently formed instead of continuously.

Next, as shown in FIG. 5(B), conductive paste 14 for external electrodes is applied to the end portion including the end face 1C and the end portion including the end face 1D of the unsintered capacitance element 11, respectively. Apply in cap shape.

Next, the unsintered capacitance element 11 (ceramic green sheet 12, conductive paste layer 13 for internal electrodes) and conductive paste 14 for external electrodes are simultaneously fired. As a result, as shown in FIG. 5(C), the ceramic green sheet 12 becomes the capacitive element 1, the conductive paste layer 13 for internal electrodes becomes internal electrodes 2 and 3, and the external electrodes The conductive paste 14 becomes the external electrodes 4 and 5.

On the other hand, the external electrodes 4 and 5 each have a letter C shape when viewed from the first cut surface. In addition, the external electrodes 4 and 5 include a first region 6 and a second region 7 when viewed in a first cut plane, and the second region 7 completely surrounds the first region 6. all. In the second region 7 in which Sn is unevenly distributed, Sn contained in the conductive paste 14 for external electrodes is melted during firing, and the outer side of the external electrodes 4 and 5 (the side in contact with the capacitor element 1, and the side in contact with the atmosphere) is formed by segregation. In the multilayer ceramic capacitor 100 of this embodiment, the second region 7 is well formed, and the second region 7 is in contact with the inner region 7a and the capacitor 1. The second region 7 completely surrounds the first region 6 with the inner region 7a and the outer region 7b.

On the other hand, in order to form the second region 7 satisfactorily, the conductive paste for external electrodes should contain 1 to 15% by weight of Sn particles when the total weight of Ni particles and Sn particles is 100% by weight. desirable. In addition, the temperature at which the unsintered capacitance element 11 (ceramic green sheet 12, the conductive paste layer 13 for internal electrodes) and the conductive paste for external electrodes 14 are simultaneously fired is about 232°C, which is the temperature at which Sn melts. It is preferably at least 1455 °C, which is the temperature at which Ni melts. When the above two conditions are satisfied, alloying of Ni particles and Sn particles is suppressed without shortage of Sn particles, and the second region 7 is formed satisfactorily. On the other hand, when alloying of the Ni particles and the Sn particles proceeds, the Sn particles are not unevenly distributed in the regions of the external electrodes 4 and 5 in contact with the capacitive element 1, so that the inner region 7a is not formed.

From the above, the multilayer ceramic capacitor 100 according to the first embodiment is completed.

(humidity load test)

In order to confirm the effectiveness of the present invention, the following moisture resistance test was conducted.

First, a multilayer ceramic capacitor 100 according to the first embodiment was manufactured, and it was set as a sample according to the embodiment. The conductive paste for external electrodes used to prepare the sample according to the embodiment contains 15% by weight of Sn particles when the total weight of Ni particles and Sn particles is 100% by weight. The number of fabricated samples according to the examples was set to 100 pieces.

Further, for comparison, a multilayer ceramic capacitor in which a part of the configuration of the multilayer ceramic capacitor 100 was changed was fabricated, and a sample according to the comparative example was prepared. For fabrication of the sample according to the comparative example, a conductive paste for external electrodes having a smaller content of Sn particles than that used for fabrication of the multilayer ceramic capacitor 100 was used. Specifically, in the preparation of the sample according to the comparative example, a conductive paste for external electrodes containing 30% by weight of Sn particles was used when the total weight of Ni particles and Sn particles was 100% by weight. The production number of samples according to the comparative example was 101 pieces.

One multilayer ceramic capacitor of the prepared sample according to the comparative example was cut at the same portion as the first cut surface, and the state of the cut surface of the external electrode was examined. In the sample according to the comparative example, the first region was formed on the external electrode. However, in the second region, which is a region in which Sn is unevenly distributed, an outer region not in contact with the capacitive element was formed, but an inner region in contact with the capacitance element was only incompletely formed. Specifically, the inner region was formed only partially, with a small thickness, and only discontinuously. As a result, in the multilayer ceramic capacitor of the sample according to the comparative example, the second region did not completely surround the first region.

Next, 100 each of samples according to Examples and Comparative Examples were mounted on a glass epoxy substrate using eutectic solder. Then, the insulation resistance value of each sample was measured.

Next, the glass epoxy substrate was placed in a high-temperature, high-humidity chamber, and a voltage of 3.2 V was applied to each sample for 72 hours in an environment of 125°C and a relative humidity of 95% RH. Subsequently, the insulation resistance value of each sample after the moisture resistance load test was measured.

In each sample, those in which the insulation resistance value decreased by 1 digit or more before and after the moisture resistance load test were counted as defective. As a result, 0 samples out of 100 were determined to be defective in the samples according to the examples. On the other hand, in the sample according to the comparative example, 10 out of 100 were judged to be defective.

The effectiveness of the present invention was confirmed by the above moisture resistance load test. That is, in the multilayer ceramic capacitor 100, when the inner region 7a of the second region 7 of the external electrodes 4 and 5 forms a plating layer on the outer surface of the external electrodes 4 and 5 or the finished product It has been confirmed that it greatly contributes to suppressing the intrusion of moisture into the capacitor 1 during use or the like.

[Second Embodiment]

5 shows a multilayer ceramic capacitor 200 according to the second embodiment. However, FIG. 5 is a cross-sectional view of the multilayer ceramic capacitor 200 . More specifically, FIG. 5 shows side surfaces 1E and 1F of the capacitor 1, in which the multilayer ceramic capacitor 200 is cut at half the length of the capacitor 1 in the width direction (W) of the capacitor 1. It represents a parallel cut plane. On the other hand, this cut surface may be called a second cut surface.

The multilayer ceramic capacitor 200 according to the second embodiment has a new structure added to the multilayer ceramic capacitor 100 according to the first embodiment described above. Specifically, in the multilayer ceramic capacitor 100, no plating layer is formed on the external surfaces of the external electrodes 4 and 5. In contrast, in the multilayer ceramic capacitor 200, a Ni plating layer 8 is formed as a first layer and a Sn plating layer 9 is formed as a second layer on the outer surfaces of the external electrodes 4 and 5. Other configurations of the multilayer ceramic capacitor 200 are the same as those of the multilayer ceramic capacitor 100 .

Meanwhile, when the multilayer ceramic capacitor 200 is also viewed from the second cut surface, the second region 7, which is a region in which Sn is unevenly distributed in the external electrodes 4 and 5, completely surrounds the first region 6.

In the multilayer ceramic capacitor 200, when forming the Ni plating layer 8 or Sn plating layer 9 or when using a finished product, the second region 7 (especially the inner region 7a) of the external electrodes 4 and 5 )) prevents moisture from penetrating into the capacitance element 1 .

In the above, the multilayer ceramic capacitor according to the embodiment has been described. However, the present invention is not limited to the above, and various changes may be made according to the spirit of the invention.

For example, although the multilayer ceramic capacitor includes two external electrodes in the above embodiment, the number of external electrodes may be increased to make a three-terminal type multilayer ceramic capacitor.

A multilayer ceramic capacitor according to an embodiment of the present invention is as described in the section "Means for solving problems".

In this multilayer ceramic capacitor, it is also preferable that the second region includes an inner region in contact with the capacitive element and an outer region not in contact with the capacitance element. In this case, the moisture resistance of the multilayer ceramic capacitor can be improved by the inner region. In addition, solder wettability of the external electrode can be improved by the outer region.

It is also preferable that at least one plating layer is formed on the outer surface of the outer region of the second region. In this case, the plating layer may contain a Sn plating layer. Further, the plating layer may include a Ni plating layer and a Sn plating layer formed on the outer surface of the Ni plating layer.

Also, when viewed in a cross section, it is preferable that the area occupied by Sn per unit area of the external electrode is larger on the outer side and smaller on the inner side. Also in this case, it is possible to suppress the penetration of moisture into the capacitor element.

A method for manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention is as described in the section "Means for Solving Problems".

In this method of manufacturing a multilayer ceramic capacitor, it is preferable that the firing temperature be higher than the temperature at which Sn melts and lower than the temperature at which Ni melts. In this case, the second region can be preferably formed on the external electrode.

1: Capacitive element
1a: ceramic layer
2, 3: internal electrode
4, 5: external electrode
6: first area
7: second area
7a: inner region
7b: outer region
8: Ni plating layer
9: Sn plating layer

Claims (8)

A pair of main surfaces having a plurality of stacked ceramic layers and a plurality of internal electrodes, facing each other in the height direction, and a pair of end faces facing each other in the longitudinal direction perpendicular to the height direction; , a capacitive element having a pair of side surfaces facing each other in a width direction orthogonal to the height direction and the length direction;
A multilayer ceramic capacitor including at least two external electrodes formed on the surface of the capacitive element,
The external electrode includes Ni and Sn,
Looking at a cut plane parallel to the side surface of the capacitive element, in which the capacitance element and the external electrode are cut at 1/2 of the length of the capacitance element in the width direction,
The external electrode is formed in a C shape on the end face of the capacitive element and the main surface connected to both sides of the end face,
The C-shaped external electrode includes a first region and a second region completely surrounding the first region,
The second region is a region in which Sn is unevenly distributed, and when a square measurement region of 10 μm × 10 μm is arbitrarily selected from the second region exposed on the cut surface, the ratio between the area of Ni exposed in the measurement region and the Sn The area of Sn relative to the total area is 90% or more,
The first region is the Sn for the sum of the area of Ni and the area of Sn exposed in the measurement region when a square measurement region of 10 μm × 10 μm is arbitrarily selected from the first region exposed on the cut surface. A multilayer ceramic capacitor wherein the area of is less than 90%. According to claim 1,
The multilayer ceramic capacitor, wherein the second region includes an inner region in contact with the capacitive element and an outer region not in contact with the capacitive element. According to claim 2,
The multilayer ceramic capacitor, wherein at least one plating layer is formed on an outer surface of the outer region of the second region. According to claim 3,
the plating layer
A multilayer ceramic capacitor comprising a Sn plating layer. According to claim 4,
the plating layer
Ni plating layer;
A multilayer ceramic capacitor comprising a Sn plating layer formed on an outer surface of the Ni plating layer. According to any one of claims 1 to 5,
When looking at the cut surface, the external electrode
The area occupied by the Sn per unit area is
A multilayer ceramic capacitor that is larger on the outer side and smaller on the inner side. A pair of main surfaces having a plurality of stacked ceramic green sheets and a plurality of conductive paste layers for internal electrodes, facing each other in the height direction, and a pair of facing each other in the longitudinal direction orthogonal to the height direction manufacturing an unsintered capacitance element having an end face and a pair of side surfaces facing each other in a width direction orthogonal to the height direction and the length direction;
A step of manufacturing a conductive paste for an external electrode containing at least Ni particles and Sn particles;
a step of applying the conductive paste for external electrodes to at least the end face of the unsintered capacitance element, and the main face and the side face connected to the end face in a cap shape;
A method of manufacturing a multilayer ceramic capacitor including a step of simultaneously firing the unsintered capacitance element and the conductive paste for external electrodes,
In the conductive paste for external electrode, the weight of the Sn particles relative to the total weight of the Ni particles and the weight of the Sn particles contained therein is 1% by weight or more and 15% by weight or less. According to claim 7,
The method of manufacturing a multilayer ceramic capacitor, wherein the firing temperature is equal to or higher than the temperature at which Sn melts and lower than the temperature at which Ni melts.